The present invention relates to a reversible control apparatus which is able to control a motor in a reversible manner in accordance with a target rotational speed thereof.
In general, a DC generator or a two-phase pulse generator is employed as a rotational speed sensor which is used with a control apparatus for controlling a motor such as a DC motor in a reversible manner so as to obtain an output signal with a positive or negative polarity in dependence upon the rotational direction of the motor.
A rotational speed sensor in the form of a DC generator is generally provided with a brush which poses problems from the standpoint of durability and weather resistance. In addition, it is desirable for a rotational speed sensor particularly suitable for use with a servo system to have a lesser inertial mass.
On the other hand, a rotational speed sensor in the form of a two-phase pulse generator requires two pulse generators, so the structure of the sensor necessarily becomes complicated, resulting in an increase in the manufacturing cost.